Smaller water drainage grids in the garden, in the courtyard, on the rain gutter or in the basement are usually referred to as small gullies. In almost all cases there is a concrete rain gully under the grille. While rain gullies made of plastic and metal often have two chambers, concrete products usually only have one chamber.
Two functions in one chamber
If you need a water drain on a sealed floor, you usually use a small drain grate. The grid forms the lid on the top of a rain gully. The water runs into a funnel-shaped interior with a collecting basket. Here, rubbish such as leaves and other foreign matter is caught so that the drain line does not clog.
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The second essential function of the rain gully is to prevent water backflow. In the two-chamber system of products made of plastic or metal, a non-return flap is often attached as additional protection. This allows the rain gully to be reduced in size, but makes it wider.
Backflow protection through chamber depth
In smaller water drains, such as those brought in garages, on parking areas, on sidewalks and in the courtyard, a rain gully made of concrete has a depth of around forty centimeters. In the event of a backwater, the water level would have to rise to this level before it would emerge from the drain grate upwards.
The installation of the rain gully is relatively easy. The drainage pipe must be laid or arrive at the depth where the lateral outlet nozzle is located. In most cases, the depth is around a foot.
Differences between concrete, plastic and metal
A two-chamber system made of plastic or metal is usually installed on rain gutters, as laying the rainwater pipe becomes easier.
The depth of the rainwater pipe can be adjusted more flexibly than with the fixed concrete component.
A greater ease of use due to the distance between the downpipe and the drainage chamber also distinguishes the two-chamber systems from the single-chamber system of the rain gully made of concrete.Tips & Tricks If you place the rain gully on surfaces that are driven on by vehicles, you should definitely choose flush, horizontal grid shapes. The drain grids, also known as grids, should also be specifically designed to withstand the load of car tires.